1. Field of the Invention
The present invention relates to the refining of hydrocarbons and particularly to the upgrading of hydrocarbon oils containing organometallic components by removing contaminant metals therefrom. More particularly, the invention relates to producing hydrocarbon products containing low concentrations of contaminant metals from oils containing high concentrations of metals.
2. Description of the Prior Art
Various hydrocarbon-containing oils which require refining, such as crude petroleum and syncrude oils, heavy vacuum gas oils, shale oils, oils from bituminous sands, topped crudes, and atmospheric or vacuum residual fractions, often contain varying amounts of metallic contaminants, such as vanadium, nickel, copper, iron, sodium, and zinc. A substantial proportion of the metals contained in such oils, especially in the asphaltene fraction thereof, are in the form of organometallic components, principally metal porphyrins and derivatives thereof. During the refining of such oils subjected to a catalytic treatment, some of the organometallic components undergo chemical reactions resulting in deposition of contaminant metals on the catalyst. The deposition of metals on the catalyst proves detrimental to many refining catalysts, causing deactivation thereof and/or loss of selectivity for yielding an intended product. In the usual instance, the extent of deactivation and/or selectivity loss is a function of the amount of metals deposition, i.e., the usefulness of the catalyst steadily decreases as the amount of deposited metals increases with continued treatment of the oil.
Ordinarily, removal of metal contaminants from oils by thermal treatment also includes the production of coke. Usually it is uneconomical to remove metal contaminants from oils if too much coke is also produced.
It is an object of this invention to provide a process for removing metal contaminants from oils. A further object is to provide hydrocarbon products of reduced metals content so as to extend the life of downstream refining catalysts.
It is another object of this invention to provide a process involving thermal treatment, for removing metal contaminants from oils but with a minimum of coke production. These and other objects and advantages of the invention will become apparent from the following description.